Developments in microarray-based detection devices have dramatically changed the biotechnology industry. The devices make it possible to analyze multiple biological samples simultaneously and detect rare transcripts in human. They also make it possible to obtain information from microarrays automatically within minutes instead of within months or even years without the help of the devices.
Microarrays typically comprise a plurality of polymers, such as oligonucleotides, peptides, and antibodies. The polymers are synthesized or deposited on a substrate in an array pattern, which can be labeled with optically detectable labels such as fluorescent tags or fluorophores. A typical microarray scanner uses laser as excitation light source, and use matching filters and photomultiplier tubes for detection. During scanning of a microarray, excitation light from the laser source hits different spots on the microarray. Fluorescent probes on the array emit Stokes-shifted light in response to the excitation light, and the emission light is collected by the photomultiplier tube. The resulting information on the microarray can be used for various purposes such as gene expression studies, mutational studies, genotyping, SNP studies, protein interaction analysis, as well as diagnosis and treatment of diseases.
Most of the microarray scanning systems use stepper motors and servo motors, which both require a linear driving mechanism to convert the rotary movement of the motors into linear movement. Traditional linear driving mechanisms include ball-screw driven mechanisms and belt driven mechanisms. Ball-screw driven mechanisms use a ball screw and a train of recirculating ball bearings contained in a nut to convert rotary movement into linear movement. Belt driven mechanisms utilize a belt that transforms the rotary movement of driving wheels into horizontal movement. When factors such as return deviation, lifetime, and load capacity are equivalent, the ball-screw driven mechanism provides medium moving speed and high precision of repetitivity, while belt driven mechanism provides high moving speed and low precision of repetitivity. Traditional microarray scanning devices thus either have a low scanning speed or a low precision of repetitivity. There is therefore a need for new scanning systems.